Some heart defects in the conduction system result in asynchronous contraction of the heart, which are sometimes referred to as conduction disorders. As a result, the heart does not pump enough blood, which may ultimately lead to heart failure. Conduction disorders can have a variety of causes, including age, heart (muscle) damage, medications and genetics.
A common cause for conduction disorders results from defects in the left and/or right ventricle fast activation fibers, the His-Purkinje system, or scar tissue. As a result, the left and right ventricles may not be synchronized. This is referred to as Left Bundle Branch Block (LBBB) or Right Bundle Branch Block (RBBB). A known way to improve heart function in case of LBBB or RBBB is cardiac resynchronization therapy (CRT), which is also known as biventricular pacing or multisite ventricular pacing. CRT involves simultaneous pacing of the right ventricle (RV) and the left ventricle (LV) using a pacemaker. To implement CRT, a coronary sinus (CS) lead is placed for LV pacing in addition to a conventional RV endocardial lead (with or without a right atrial (RA) lead). The basic goal of CRT is to improve the mechanical functioning of the LV by restoring LV synchrony in patients with dilated cardiomyopathy and a widened QRS period, which is predominantly a result of LBBB.
Currently, the proper positioning of leads to obtain maximum cardiac synchronization involves a certain amount of guesswork on the part of an operating physician. In particular, current methods do not allow for the determination of the optimal location for pacemaker leads, on a patient by patient basis. Further, current methods do not allow for the real time determination of whether leads have been properly positioned.
The lack of such a method may contribute to the 30% of patients that fail to respond to CRT. Accordingly, there is a need for improved CRT methods.